1. Field of the Invention
The present invention relates to methods for the separation of rare earth elements from aqueous solutions and, more particularly, to the separation of lanthanides (e.g., neodymium(III)) from aqueous solutions using an organo phosphorus functionalized adsorbent.
2. Description of the Related Art
Rare earth metals are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium, and the fifteen lanthanides. Scandium and yttrium are also considered rare earths because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. Furthermore, the study of rare earth elements (“REE”) is relevant in the separation of REE/lanthanides from actinides in the treatment of spent nuclear fuels because actinides, especially Am(III) and Cm(III), have similar geochemical properties as REE.
Over the past several decades the demand for rare earths has increased and the necessity for the high purity of these elements requires the selective separation of the lanthanides which is thus still of great interest and importance. The separation of lanthanides is a difficult task because of their similar chemical structure and physical properties.
Extraction and pre concentration of these valuable ions from wastes are extremely important not only from the view of their limited resource availability, but also for the reduction of their quantum for disposal as radioactive wastes. Numerous processes have been applied for effectively reducing lanthanide ions from various aqueous solutions including ion exchange, chelating polymer resin, solvent extraction, and adsorption.
Description of the Related Art Section Disclaimer: To the extent that specific publications are discussed above in this Description of the Related Art Section or elsewhere in this application, these discussions should not be taken as an admission that the discussed publications are prior art for patent law purposes. For example, some or all of the discussed publications may not be sufficiently early in time, may not reflect subject matter developed early enough in time and/or may not be sufficiently enabling so as to amount to prior art for patent law purposes. To the extent that specific publications are discussed above in this Description of the Related Art Section (as well as throughout the application), they are all hereby incorporated by reference into this document in their respective entirety(ies).